Figure 3.
Comparison of the interaction energy (ΔE) for 1,250 methanol clusters, including 999 clusters of 9 molecules, 157 clusters of 11 molecules, and 94 clusters of 13 molecules, computed from (a) MP2/6-31G(d,p) (b) DFMP2(fc)/jul-cc-pVDZ, and (c) DFMP2(fc)/jul-cc-pVTZ and the optimized force field model fitted without the offset parameter δ in Eq. (2). (d), (e) and (f) are the optimized force field model fitted with the offset parameter δ in Eq. (2).